Sous vide ("under vacuum") food preparation techniques are becoming increasingly popular in the food service and restaurant industries. With sous vide food preparation, restaurants or other food service establishments are able to serve a wide selection of high quality, gourmet food items with minimal on-site cooking and preparation.
In the sous vide process, food and spices are contained in thermo-retractable pouches which are evacuated and sealed. Typically the food is placed in the pouches at a factory location remote from the food service establishment. The sealed pouches are then slowly cooked in the factory at low temperatures to enhance flavor and texture. The pouches are then flash frozen and shipped to the restaurants and food service establishments.
The frozen pouches arriving at the food service establishment are stored until the food is to be served. At this time, the pouches are placed in a sous vide rethermalization appliance. The appliance typically contains one or more water containment tanks or vats. In accordance with the sous vide process, a pouch to be reheated is placed in a first vat and heated to bring the internal temperature of the food to approximately 180.degree. F. Immediately prior to serving the food, the pouch is placed in a second vat and heated for a predetermined time at approximately 200.degree. F. The exact temperatures of course, depend upon the type and texture of the food being heated. After the food is cooked, the pouch is removed from the vat, opened, and the food transferred to a plate for serving.
Such a device for reheating sous vide food pouches is disclosed in U.S. Pat. No. 5,097,759 entitled "Sous Vide Reheating Device" and issued to Vilgrain et al. The device includes first and second water heating chambers, each including an electrical heating element and a thermostat to control the temperature of the water therein. The first chamber is arranged to preheat sous vide pouches and has a water bath which is maintained at a first predetermined temperature preferably of about 135.degree. F. to about 140.degree. F. The second chamber is arranged to quickly heat the sous vide pouches immediately prior to serving and has a water bath which is maintained at a second predetermined temperature preferably between 160.degree. F. to about 165.degree. F.
A timer control unit is provided above each unit. Each timer control unit receives a signal from the thermostat indicating the temperature of the water in the chamber and varies the time for each pouch depending upon the difference between the actual temperature of the water and the predetermined temperature. Each chamber is preferably divided into a plurality of sub-chambers with each sub-chamber having an associated timer to measure the amount of time elapsed for that sub-chamber.
Water level changes in the rethermalizer are primarily due to insertion and removal of bags in the vats. The precise water level is often difficult to determine by visual inspection alone as dividers commonly used to separate numerous pouches in the vats obstruct the view of the operator. Visual water level monitoring also requires substantial time and effort by the system operator.